Method and device for regulation of a cooling fan drive on an internal combustion engine in a construction or working machine

ABSTRACT

The invention relates to a method for regulation of a cooling fan drive on an internal combustion engine, in particular equipped with several independent cooling circuits, in a construction or working machine, whereby the power drain of the cooling fan drive is set to approximately zero during certain working stages of the construction and/or working and said power drain may be added to the capacity for the working stage.

[0001] The invention relates to a method for regulating a cooling fandrive on an internal combustion engine, in particular provided with anumber or separate cooling circuits and used in construction or workingmachines.

[0002] German reference DE-A 195 35 674 proposes a method for regulatingthe cooling system of an excavator drive, in particular ahigh-performance diesel-engine drive. For this method, a thermostatprovided near the diesel engine opens up the flow path from the dieselengine to a water cooled-radiator that operates jointly with the fan ata predetermined water temperature. A temperature gauge arranged in thearea of the flow path controls the fan in such a way that within apredetermined temperature range above the thermostat-controlled watertemperature, the speed of the fan is controlled in the range between 0min⁻¹ and a maximum speed.

[0003] German reference DE-A 198 25 759 discloses a hydraulic drivecomponent with a variable displacement pump that is connected flow-wisein a closed circuit to an engine and is designed to drive an auxiliarydevice such as a fan. An auxiliary pump can be connected operationallyto the pump, the engine and a container for replenishing the flow mediumlost in the closed circuit. An auxiliary circuit that is connected tothe pump has a circulation opening that is connected with respect to theflow to the closed circuit in downstream direction of the engine, so asto reduce the required container volume.

[0004] Construction or working machines, particularly hydraulicexcavators, are designed for specific peak performances, for examplecomputed on the basis of identical working movements that are in partrepeated constantly, such as the lifting of the boom and the pivoting ofthe upper carriage relative to the undercarriage.

[0005] The internal combustion engines of these construction or workingmachines, in particular of hydraulic excavators, are normally cooledwith water, wherein a fan controlled by a separate hydraulic drive isprovided. The fan can be turned on/turned off and, in particular, can beactuated by the internal combustion engine in dependence on theincreasing temperatures in the cooling circuit of the internalcombustion engine.

[0006] During normal operations of the construction or working machine,particularly of the hydraulic excavator, the fan as a rule is activatedonce a predetermined temperature value is exceeded in the coolingcircuit of the internal combustion engine. The activated fan requires aspecific driving power for controlling the temperature in the coolingcircuit.

[0007] As a result of the power drain caused by the fan activation, thefull driving power of the internal combustion engine is not available,for example, for raising a boom and the internal combustion enginecapacity assigned to the operating sequence may no longer be sufficientfor certain limit ranges.

[0008] Thus, it is the object of the invention to provide a method and adevice for regulating a fan drive in such a way that the capacity can beraised for the working movements of the construction or working machine,without this leading to a reduction in power for the internal combustionengine.

[0009] This object is solved with a method for regulating a fan drive onan internal combustion engine, in particular provided with severalindependent cooling circuits, in construction and/or working machines.For this, the power consumption of the fan drive is set to approximatelyzero for predetermined operating sequences of the construction and/orworking machine and the fan power consumption is added to that of theoperating sequence.

[0010] Advantageous modifications of the subject matter of the inventionfollow from the associated dependent method claims.

[0011] This object is furthermore solved with a device for regulating afan drive on an internal combustion engine, in particular provided withseveral independents cooling circuits and used in construction and/orworking machines. The device comprises at least one PI regulator foreach cooling circuit, at least one downstream-connected comparator, aswell as at least one pulse-width modulator that is operatively connectedto a control unit.

[0012] The regulator according to a different idea behind the inventionis a μ controller-PI regulator.

[0013] The subject matter of the invention makes it possible to adjustat least two different set temperature values for several independentlyoperating cooling circuits in an internal combustion engine with the aidof a fan drive and via a joint control unit. As a result, the powerconsumption of the fan drive is set to zero for specific workingmovements (fan runs along with no load) and the fan capacity can then beadded to that of the working movement.

[0014] A set value/actual value comparison is performed with a μcontroller-PI regulator for each cooling circuit and the requiredadjustment value is determined for each cooling circuit. Thedownstream-connected comparator then determines the maximum adjustmentvalue from the individual adjustment values and transmits this maximumvalue to a PWM stage (pulse width modulation stage) that is connected tothe control unit. For a specific working movement, for example whenraising the boom of a hydraulic excavator, the set temperature values ofthe cooling circuits are essentially raised simultaneously. As a result,the power consumption of the fan drive is set to approximately zero (fanruns along with no load) and the lifting capacity increases by theamount of the fan drive capacity.

[0015] Depending on the dimensions of the construction or workingmachine, in particular a large hydraulic excavator, the lifting capacityfor raising the boom can thus be increased without overheating of thedrive unit or units. This takes into account that the fan driving poweris not assigned continuously, but is required only for predetermined,defined working movements of the construction or working machine.

[0016] The single FIGURE is described in the following and represents aschematic diagram.

[0017] Shown is an internal combustion engine 1, provided for thisexample with two independent cooling circuits 2, 3, which in turn areconnected via a controller 9 with control unit 10 on a controllable fandrive 4 to a fan wheel 5. Also shown is an equipment part 6, for examplethe boom of a hydraulic excavator that is not shown in further detailherein. This equipment part is positioned on an upper carriage 7 that isonly indicated herein and can be lowered or raised with the aid ofhydraulic cylinders 8. Also indicated are the hydraulic circuit 11,which is responsible for the lifting and lowering of the equipmentcomponent 6, the hydraulic circuit 12 that is responsible for the fandrive 4, as well as the hydraulic circuit 20 that is necessary forsupplying the control unit 10. A μ controller-PI regulator 13, 14 isprovided for each cooling circuit 2, 3, which performs a setvalue/actual value comparison and computes the associated adjustmentvalues for each cooling circuit 2, 3. The set values are provided to theμ controllers-PI regulators 13, 14 via a reversing switch 15. The valuesdetermined by the μ controllers-PI regulators 13, 14 are transmitted toa downstream-connected comparator 16. This comparator determines themaximum adjustment value from the individual adjustment values andtransmits this maximum adjustment value to a PWM (pulse widthmodulation) stage 17 that is connected via the line 18 to the controlunit 10. Among other things, a portion of the driving capacity of theinternal combustion engine 1 is thus assigned to the operating sequenceof the equipment component 6 while another portion of the drivingcapacity is required for the fan wheel 5, so as to protect the internalcombustion engine 1 against overheating. For specific operatingsequences, for example when raising the equipment component 6 with theaid of hydraulic cylinders 8, the combustion engine 1 may not haveenough driving power for raising the equipment component 6.

[0018] According to the invention, a switch 19 and the reversing switch15 are used to raise the set temperature values for the cooling circuits2, 3 for this type of working movement to higher set temperature values.As a result, the power consumption of the fan drive 4 is set toapproximately zero via the line 18 and the control unit 10. The fanwheel 5 then stops running or runs along without load. The hydraulicdriving power of the fan drive 4, which is no longer needed foroperating the fan wheel 5, is thus added to the lifting capacity of theequipment component 6 without resulting in overheating of the internalcombustion engine 1. As soon as the specific movement sequence iscompleted, the hydraulic fan drive 4 is again switched to the fan wheel5, wherein the increased set temperature values for each cooling circuit2, 3 are again assigned via the switch 19 and the reversing switch 15 toa lower set temperature value. This power interplay can be repeated inan optional sequence, but must be seen in the final analysis asdepending on the maximum capacity to be assigned to the respectivemovement sequence.

1. (Original) A method for regulating a fan drive (4) on an internalcombustion engine (1), in particular provided with several independentcooling circuits (2, 3) and used in construction and/or working machinesin that the power consumption of the fan drive (4) is set approximatelyto zero for predetermined operating sequences of the construction and/orworking machine and that the fan power consumption is added to that ofthe operating sequence.
 2. (Original) The method according to claim 1,characterized in that at least two different set temperature values areadjusted for the cooling circuit (2, 3), wherein for predeterminedoperating sequences of the construction or working machine the one settemperature value is adjusted to a higher set temperature value with theaid of a switch (19) and a reversing switch (15) and that the operatingcapacity of the fan drive (4) is set to approximately zero. 3.(Currently Amended) The method according to claim 1 or 2, characterizedin that if several cooling circuits (2, 3) exist, at least two differentset temperature values are adjusted for each cooling circuit (2, 3) viaa joint control unit (10).
 4. (Currently Amended) The method accordingto one of the claims claim 1 to 3, characterized in that a setvalue/actual value temperature comparison is carried out with a μcontroller-PI regulator (13, 14) for each cooling circuit (2, 3) andthat the permissible adjustment value for each cooling circuit (2, 3) isdetermined.
 5. (Currently Amended) The method according to one of theclaims claim 1 to 4, characterized in that a comparator (16) thatoperates jointly with the PI regulator(s) (13, 14) determines a maximumadjustment value from the individual adjustment value(s) and transmitsthis maximum adjustment value to a pulse width modulation stage (17)that is operatively connected to the control unit (10).
 6. (CurrentlyAmended) The method according to one of the claims claim 1 to 5,characterized in that for a predetermined working movement of theconstruction and/or working machine, in particular for lifting the boom(6) of a hydraulic excavator, the set temperature values of all coolingcircuits (2, 3) are raised essentially at the same time, thus causingthe power consumption of the fan drive (4), particularly during theno-load operation of the fan wheel (5), to be set approximately to zeroand the driving power of the fan drive (4) to be assigned to themovement sequence of the construction and/or working machine, inparticular for increasing the lifting capacity of the boom (6). 7.(Original) A device for regulating a fan drive (4) on an internalcombustion engine (1), in particular provided with several independentcooling circuits (2, 3) and used in construction and/or workingmachines, said device comprising at least one reversing switch (15), atleast one PI regulator (13, 14) for each cooling circuit (2, 3), atleast one downstream-connected comparator (16), as well as at least onepulse width modulator (17) that is operatively connected to a controlunit (10).
 8. (Original) The device according to claim 7, characterizedin that the regulator (13, 14) is a μ controller-PI regulator.